1. Field of the Invention
A method, system, and program for converting a list of input parameters for a command to a list of output parameters that include a different number of parameters than the input list.
2. Description of the Related Art
Data storage systems often include a feature to allow users to make a copy of data at a particular point-in-time. A point-in-time copy is a copy of the data consistent as of a particular point-in-time, and would not include updates to the data that occur after the point-in-time. Point-in-time copies are created for data duplication, disaster recovery/business continuance, year 2000 testing, and decision support/data mining and data warehousing, application development and testing.
One data duplication technique for such storage controller systems that manage access to massive storage devices is the International Business Machines Corporation (IBM) SNAPSHOT** program. SnapShot is intended for use with the IBM RAMAC Virtual Array or ICEBERG disk storage systems.** Such systems provide a virtual disk architecture, also referred to as Log Structured Array (LSA) system, in which mappings provide virtual locations of the data. LSA tables map host tracks to disk array storage locations where the data is stored. When data is written to the system, it is compressed and compacted, assembled into fixed blocks, and written to the DASD. All write operations in virtual disk architecture are always directed to a new place in the disk array. SnapShot operates by copying the LSA pointers to the data, and not copying the actual data. Thus, after a SnapShot copy is made, there are two sets of pointers to the same data. Further details of the SnapShot operation are described in the IBM publications “Implementing Snapshot,” IBM document no. SG24-2241 (IBM Copyright, November 1997); “Using RVA and SnapShot for Business Intelligence Applications with OS/390 and DB2,” IBM document no. SG24-5333-00 (IBM Copyright, August 1998), which publications are incorporated herein by reference in their entirety.
**ESA/390 is a trademark of IBM and RAMAC is a registered trademark of IBM; Iceberg is a registered trademark of Storage Technology Corporation. 
When copying the LSA pointers as part of a SnapShot operation, the storage controller must take into account any control data maintained in tracks that are subject to a copy operation. One such control data set that must be accounted for is the Volume Table of Contents (VTOC). The VTOC is a data set that resides on a DASD volume and describes the contents of that volume. The VTOC is comprised of data set control blocks (DSCBs) that describe the type and/or location of data sets on that volume of contiguous areas of unassigned space. The VTOC may reside at different locations on a DASD volume. Each volume in the DASD has a unique VTOC
The commonly assigned and related patent application, entitled “System for Multiple Data Transfer Operations,” to David C. Reed and John G. Thompson, having Ser. No. 09/045,138 now U.S. Pat. No. 6,209,070 and filed on Mar. 20, 1998, which application is incorporated herein by reference in its entirety, describes a copy method in an LSA environment for handling VTOC tracks included in the range of tracks to Snapshot copy. This method comprises first copying control data, such as the VTOC, from a source to target functional volumes in the LSA virtual space and then, after completing the first operation, copying the pointers to the data to the target storage locations.
Although, SnapShot has proved to be an advantageous program for point-in-time copies, SnapShot only operates on a virtual disk architecture, such as an LSA architecture, where tables of pointers to the data are maintained and available for duplication.
There is thus a need in the art to provide improved point-in-time copy methods to systems that do not have an LSA type virtual array, such as home area systems, as well as LSA type data systems that utilize virtual arrays.